I've been trying to figure out why my water in my shower drain doesn't flow through the elbow. When I turn the elbow sideways the water flows correctly but sewer gasses emits out the empty elbow sideways.

Do I need to install a Air Admittance valve for this drainage problem? I have nowhere to run vent pipes in this location. If so, do I need 3 separate AAV's for toilet, shower and sink?

  • 1
    Sounds like your drain isn't vented properly Nov 5, 2015 at 23:52
  • Could you clarify what elbow you're talking about? Stack exchange loves photos.
    – Bryce
    Oct 6, 2016 at 4:18

1 Answer 1


Yes it sounds like you do need to install the air admittance valve, and yes you may need to add more, depending on the distances the other drains are from the one you plan to install. I know for toilets the max is 5 ft. Sinks may be 3 ft., but that is almost a guess, I have moved more toilets than sinks.

  • It also sounds like a p trap is needed.+
    – Ed Beal
    Oct 2, 2018 at 13:50

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